(a) Field of the Invention
The present invention relates a diagnosis device, a diagnosis method, and a lamp ballast circuit using the same.
(b) Description of the Related Art
A lamp has a filament equivalent resistance that increases at the end of a lamp life compared with that at a normal state of the lamp.
If a regular amount of current is applied to the lamp after the filament equivalent resistance increases, the increment of filament equivalent resistance causes more current loss. The increment of filament equivalent resistance also increases heat that is generated from a filament. Therefore, a temperature of the filament increases. Also, the longer a time of using the lamp is, the more the temperature of the filament increases at the end of lamp life. The increased temperature of the filament melts down plastic parts that contact the filament. In this case, connection of the lamp and fixing parts that fix the lamp becomes weaken. As a result, the lamp may be separated from the fixing parts.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.